Modern electronic systems involve different circuits and networks, where the voltage or current levels of signals conveyed along links between components or circuits are often adjusted. Signal amplifier circuits are one type of circuit that is used to adjust the voltage or current levels of signals along a link, where the goal of signal amplification is to increase signal strength without introducing errors like offset voltage, noise, distortion, etc. There are several different signal amplifier topologies, each suitable for different scenarios.
One signal amplifier topology is referred to as a chopper amplifier. In an example chopper amplifier topology, the chopping frequency is a function of the bandwidth (increasing the bandwidth necessitates an increase in the chopping frequency).
Unfortunately, increasing the chopping frequency of a chopper amplifier to increase the bandwidth results in an undesirable increase in the input bias current. The input bias current is directly proportional to chopping frequency as the chopping frequency determines the number of times a charge-transfer occurs per second on the inputs. This is because charge transfer from clock-feedthrough and charge-injection from the input chopper switches contribute to an increased input bias current in chopper amplifiers. To the extent the input bias current level interacts with an input source's impedance, an error voltage is introduced in the signal path.